Over the past decade, Amazon has shifted to transport most of its own packages, which has led to a boom in the prevalence of its delivery vans and corporate presence. However, the fragility of shipping networks has exposed a vulnerability to choke point labor organizing. Workers at Amazon centers that are threatened by choke points have won concessions from the company like pay raises and increased worker power in recent years by organizing walk outs. When these workers walk out, it is more costly to the company because it delays package deliveries.
See "Amazon's prevalence across the US makes the company vulnerable to choke point labor organizing", Noam Scheiber, New York Times, May 19, 2023